Points of sail, apparent wind, telltales, sail trim and reefing — why the boat does what it does.
A sail is a wing, and most of sail trim follows from that one idea. These guides work through it in order: the points of sail and apparent wind, the two turns — tacking and jibing — and the commands that go with them, what the telltales are showing you, what each trim control actually does, and how to recognise when it is time to reef.
They pair with the sail trim and points-of-sail modules in the Basic Keelboat Theory course, where the same ideas become exam-style questions.
Ready to test yourself? The Basic Keelboat Theory course turns these topics into 580+ practice questions with explanations.
Sailing skills
Tacking turns the bow through the wind; jibing turns the stern through it. Diagrams of both, the commands crew expect, why the boom swings hard in a jibe, how to control it, and a short knowledge check.
8 min read
Sailing skills
The points of sail from close-hauled to a run, the no-sail zone, and the difference between true and apparent wind — with an interactive explorer and the vector picture that explains why your tacking angle is wider than you expect.
9 min read
Sailing skills
Telltales are airflow gauges, not magic. What attached and separated flow look like, what each telltale pattern means, when to trim and when to steer, and how leech telltales reveal twist — with an interactive trainer.
10 min read
Sailing skills
Sheet, traveller, vang, outhaul, halyard and Cunningham, jib cars and backstay — what you move, what changes in the sail, what the boat feels like, and when you would use each. Fundamentals first, racing detail later.
11 min read
Sailing skills
There is no universal reef-at-X-knots rule, and no training body publishes one. What overpowered actually looks and feels like, why sailors reef early, the usual order of sail reductions, and how rig and crew change the answer.
9 min read
